1. Field of the Invention
The invention relates to a compressor system having a toothed wheel gear inserted in the drive train between a drive unit and a compressor region of the system, the toothed wheel gear comprising a transmission housing, a transmission input shaft supported in the transmission housing, a main gearwheel near the input and at least one output shaft, with an axle, driven by way of a pinion and leading from the main gearwheel to the compressor region.
2. The Prior Art
Such a transmission/turbocompressor system has recently been required to attain pressure conditions of P.sub.A /P.sub.E =60 and more, P.sub.E signifying the pressure in the compressor input and P.sub.A the pressure in the compressor output. This requires the transmission of great torques at medium speeds for compressor stages compressing at a low pressure level and very high speeds for compressor stages compressing at a higher pressure level. These very high speeds cannot be attained by single-stage transmissions alone. Therefore, the compressor units must be driven by a single-stage transmission in some stages and by a two-stage transmission in other compressor stages.
A transmission of the aforementioned type is disclosed in German Patent DE-C2 4,003,482. In this known device, a two-stage intermediate wheel, which is in engagement with the main gearwheel by a small-diameter annular gear and in engagement with a pinion of an output shaft by a large-diameter annular gear, is provided for the drive of a high-speed compressor unit.
Another device of the type referred to is disclosed in DE U 9,201,858. There, a triple gearwheel meshes with the main gearwheel near the input, specifically, with its axially central annular gear having a small number of teeth, while the two annular gears, located axially at the end and each having a greater number of teeth, are each in engagement with a pinion of an output shaft.
When, in these known devices, an output thrust is exerted on the output shaft of a compressor unit or, alternatively, of two compressor units mounted at the two ends of the output shaft, the resulting thrust can be transmitted by pressure plates to the crown gear meshing with the pinion. This is an advantageous accomplishment per se, because relatively small relative motions occur at the point of transmission between the pressure plates and a contact region of the crown gear near the teeth, so that comparatively low friction losses are to be expected there as compared with friction losses that would have to be expected if one wanted to support the output shaft by bearings transmitting axial thrust. As advantageous as this solution may be for the reasons indicated above, however, a certain problem nevertheless remains, inasmuch as resulting axial thrust, which is transmitted by a pressure plate to a crown gear inserted before the pinion, leads to a tilting moment on the wheel members belonging to the crown gear, which may give rise to improper positions that are hard to control.
An additional disadvantage of the known prior art devices consists in that double or triple wheels increase the width of the housing. Hence the "bending length" of the output shafts provided with pinions is also increased, which may lead to uncontrollable vibrations.
Another disadvantage of the known devices is that the housing, which should be designed for compactness and rigidity, becomes larger and therefore requires additional stiffening measures. Due to the increase in size and the addition of stiffening means, the transmission housing becomes increasingly larger and harder to handle.